Improvement in locks



UNITED STATES PATENT OFFICE.

JOHN M. PERKINS, OF CLEVELAND, OHIO.

lMPROVEMENT IN LOCKS.

Figure 1 is a side view with the cap A re-4 moved. Fig. 2 is also a side view showing the Aposition of the bolt when locked. Fig. 3 is a section in the direction ofthe linex av in Fig. 1. The nature of my invention relates to such a construction of the lock that it cannot be opened from the outside even with a key, or picked by any instrument when locked upon the inside, the lock having two key-holes that upon the outside being completely closed in the act oflocking upon the inside, thus forming a burglar-proof lock.

D is the bolt. Upon the upper side of this and within the lock are three notches, DD2 D3.

G is a sliding plate, to which the catch II is attached. This catch is pressed downward by the spring I, and tits into either of the l notches D', D, or D3.

There are two key-holes, one upon the inside and the otherupon the outside of the lock. The one shown at B is upon the outside, and is so situated in relation to thebolt D that in turning the key the nib of the key iits into the notch a in the under side of the bolt and moves the bolt outward to the position indicated by the dotted lines a a2 in Fig. l. Vhile the bolt is being moved the catch I-I is lifted by means of the nib of the key pressing against the lower edge of the slider G, which is formed into a curve, G', to avoid raising the catch H higher than is needed to clear the notch D', and the nib of the key at the same time that it raises the catch from the notch D shoves the bolt forward and the catch VH falls into the notch D, thus moving the bolt from D to D2. (-Indicated also at a a in Fig. l.

C represents the key-hole for the inside of the lock, and is placed anterior to and a little above the key-hole B, and is so situated as regards the bolt D that the nib of the key will tit into the notch e, andv as the key is rotated the nib of the key presses against the curved edge G2 of the sliding plate G, raises the catch H, and shoves the bolt D forward from the notch D to the notch D3, Fig. 2, causing the bolt to project from the lock from e to e2, or twice as far as when the key is turned in the key-hole B.

E represents a guard which projects downward from the lower edge and posterior end of the bolt D. and is so situated in regard to the key-hole B that when the key. is turned in the key-hole C (upon the inside) the guard E is caused to completely cover the key-hole B upon the inside of the lock, so that no key or other instrument can be introduced from the outside, thus making an impregnable lock.

The guard E can be made of chilled iron or hardened steel to guard against drilling or cutting away.

The key-holes from either side only go into the lock, and not through the door, as in the common door-lock.

This lock may be mortised into the edge of the door; or it may be put on with screws, in the usual manner.

The object in having the bolt D moved a greater distance whenlocked from the inside is, that the guard E may thus be caused to cover the key-hole B; but in locking from the outside the bolt moves a less distance, and the guard E is not brought over the keyhole B.

What I claim as my improvement, and desire to secure by Letters Patent, is-

Placing the key-holes on opposite sides of the lock at unequal distances from the bolt, in combination with the bolt and guard constructed and arranged substantially as and for the purpose set forth.

JNO. M. PERKINS.

Witnesses:

W. H. BUEEIDGE,

HENRY VoTH. 

